this post was submitted on 16 Dec 2023
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Stat command shows birth after modify time? (lemmy.nz)
submitted 11 months ago by luthis@lemmy.nz to c/linux@lemmy.ml
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Any explanation on how this happens?

Access: 2023-12-14 07:57:28.376736001 +1300 Modify: 2023-12-14 07:50:20.783207177 +1300 Change: 2023-12-14 07:51:57.413989824 +1300 Birth: 2023-12-14 07:51:57.413989824 +1300

Just as a matter of curiosity

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[–] cbarrick@lemmy.world 14 points 11 months ago* (last edited 11 months ago) (2 children)

FWIW, the stat structure in Linux does not include birth time [1]. It only gives you:

  1. atime: The time of last access.
  2. mtime: The time of last modification.
  3. ctime: The time of the last change to the inode.

I assume the stat command is using a filesystem-specific method to get the birth time.

Anyway, I don't think any of these stats is guaranteed to be consistent with the rest (or even correct). For example, it is common to disable atime tracking to improve I/O performance.

Assuming the data is accurate, I think the other comment about the file being a copy is the best explanation.

[–] duncesplayed@lemmy.one 4 points 11 months ago (1 children)

The stat command is using statx, which gives you a slightly different struct. statx is the cool new Linux-only system call for stat-ing. Not every filesystem will support the new btime field. (And, as you correctly say, many of those time fields are wrong, anyway)

[–] cbarrick@lemmy.world 2 points 11 months ago

Ooo neat. I was not aware of this syscall. TIL!

[–] skullgiver@popplesburger.hilciferous.nl 1 points 11 months ago

The struct returned by stat doesn't, but statx contains creation time as well as well. I believe ext4 is already tracking the creation time even if stat can't provide it.

The stat command on modern distros should get you this additional metadata, unless you use an FS that doesn't track or expose it, of course.